Method and apparatus for dehumidifying air

ABSTRACT

A novel method and apparatus to dehumidify air provides enhanced dehumidification efficiency over conventional dehumidification apparatuses. A reusable dehumidification element disk provides a disk section to strip water from an air stream. The disk is rotated so that the saturated disk section enters a separate chamber where the water can be stripped from the disk with a stream of regeneration air. The regeneration air stream is recycled and is not split from or mixed with the air stream requiring dehumidification. The result is a more efficient dehumidification than in appara- tuses which require the influent air stream to be divided into separate streams for dehumidification and regeneration functions.

This application as a continuation of co-pending appli- cation Ser. No.09/014,611, filed on Jan. 28, 1998, the entire contents of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to a method and apparatus fordehumidifying air.

II. Description of the Related Art

A conventional dehu-midification apparatus is disclosed in JapaneseLaid-open Patent Application (Kokai) No. H8-155247.

As shown in FIGS. 1 and 2, with the dehumidification apparatus disclosedin Japanese Laid-open Patent Applica- tion (Kokai) No. 6-324015, a partof the air to be dehumidified, which was inhaled into a housing B of theapparatus by a fan A is transferred to a dehumidification rotor Crotatably mounted in the housing B. After dehu- midification by therotor C, the dehumidified air is dis- charged to the outside of thehousing B. The other part of the inhaled air is passed through passagesF of a heat exchanger E and then transferred to the dehumidificationrotor C through a heater G to regenerate the dehumidification rotor C.The air humidified by the regeneration of the dehumidi- fication rotor Cis then sent to passages H of the heat exchanger E so as to condense themoisture, and the water. generated by the condensation of moisture isremoved.

However, this apparatus has the following drawbacks:

First, since the humid air generated by the regeneration of thedehumidification rotor C is cooled in the passages H of the heatexchanger E by the air in the vicinity of the housing B to thetemperature not higher than the dew point, the air at the exit of thepassages H has a temperature somewhat higher than the ambienttemperature and has a relative humidity of 100%, so that it containsmore moisture than the air in the vicinity of the housing B. Thus, sincethis humid air cooled by the heat exchanger is discharged to the outsideof the housing B as it is, the dehumidification efficiency is not high.Even if the humid air is not discharged but inhaled by the fan A, thehumid air is mixed with the air in the vicinity of the housing B, thedehumidification efficiency cannot be greatly promoted.

Second, since the air inhaled by the fan A is divided into two streamsand sent to the dehumidification rotor C and heat exchanger E,respectively, the pressure at the entrance of passages K of thedehumidification rotor C is about the same as the pressure at theentrance of the passages F of the heat exchanger E, and the pressure ishigher than that of the air in the vicinity of the housing B. The airsent to the passages F of the heat exchanger E is sequentially passedthrough the heater G, the passages I of the dehumidification rotor C andthe passages H of the heat exchanger E, the pressure is sequentiallydecreased accordingly, and the pres- sure of the discharged air is aboutthe same as the air in the vicinity of the housing B. Thus, the pressureat the exit of the passages I of the dehumidification rotor C is lowerthan the entrance of the passages K of the dehumidification rotor C.

Therefore, the air in the vicinity of the entrance of the passages K ofthe dehumidification rotor C flows to the exit of the passages I of thedehumidification rotor C and the temperature and humidity of the humidair generated at the dehumidification rotor C are both decreased, sothat the amount of the removed moisture is decreased.

Third, since the air discharged from the passages K of thedehumidification rotor C is immediately discharged to the outside of thehousing B, the pressure in the vicinity of the exit of the passages K ofthe dehumidification rotor C is about the same as the pressure outsidethe housing B. Thus, the pressure at the entrance of the passages I ofthe dehu- midification rotor C is higher than the pressure at the exitof the passages K of the dehumidification rotor C. Therefore, a part ofthe air heated by the heater G in the vicinity of the entrance of thepassages I of the dehumidification rotor C flows to the exit of thepassages K of the dehumidification rotor C and the amount of the humidair generated by the dehumidification rotor C is decreased, so that theamount of the removed moisture is decreased.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a methodand apparatus for dehumidifying air by which air is dehumidified with ahigher efficiency than the conventional dehumidification apparatuses.

The present inventor intensively studied to discover that thedehumidification efficiency can be promoted by provid- ing air usedentirely for regeneration of the dehumidification rotor and bysubstantially separating the air for regeneration of thedehumidification rotor from the air to be dehumidified and from thedehumidified air, thereby completing the present invention.

That is, the present invention provides a method for dehumidifying aircomprising the steps of:

-   -   (i) contacting a dehumidification element which revers- ibly        absorbs moisture in the air and which is contained in a housing        of a dehumidification apparatus, with the air to be        dehumidified;    -   (ii) discharging air to the outside of said housing, which air        was dehumidified by the contact with said dehu- midification        element;    -   (iii) regenerating said dehumidification element by con- tacting        said dehumidification element after absorbing the moisture in        said air with heated air for regeneration of the        dehumidification element so as to remove the moisture from said        dehumidification element;    -   (iv) reusing the dehumidification element in the step (i), which        was regenerated by the step (iii);    -   (v) cooling the air for regeneration of the dehumidifica- tion        element after removing moisture from the dehu- midification        element in the step (iii) so as to condense the moisture, and        removing the generated water from the air for regeneration of        the dehumidification ele- ment; and    -   (vi) circulating the air for regeneration of the dehumidi-        fication element from the step (v) from which the water        generated by condensation of moisture was removed, to the step        (iii);        said air for regeneration of the dehumidification element is not        substantially mixed with the air to be dehumidified or with the        dehumidified air.

The present invention also provides a dehumidification apparatuscomprising:

-   -   a housing;    -   a dehumidification element which reversibly absorbs moisture in        the air;    -   a passage for circulating air for regeneration of the        dehumidification element, which is communicated to said        dehumidification element;    -   means for introducing the air to be dehumidified to said        dehumidification element; and    -   a dehumidified air-discharging passage for discharging the air        dehumidified by said dehumidification element to the outside of        said housing, which is communicated to said dehumidification        element and to the outside of said housing;    -   said passage for circulating air for regeneration of the        dehumidification element is provided with means for cooling the        air for regeneration of the dehumidification element after        regenerating the dehumidification ele- ment so as to condense        the moisture removed from the dehumidification element; means        for removing water generated by condensation of moisture from        the air for regeneration of the dehumidification element; a        heater for heating the air for regeneration of the dehumidifi-        cation element after removing the water generated by        condensation of moisture; and driving means for cir- culating        the air for regeneration of the dehumidification element;    -   said passage for circulating air for regeneration of the        dehumidification element is closed anywhere except for the        vicinity of said dehumidification element.

By the present invention, since the air entirely used for regenerationof the dehumidification element is separately employed and is circulatedwithout being discarded and without being substantially mixed with theair to be dehu- midified or with the dehumidified air, thedehumidification efficiency is significantly higher than those with thecon- ventional dehumidification apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut off perspective view of a knowndehumidification apparatus,

FIG. 2 shows a circuit of the known dehumidification apparatus shown inFIG. 1,

FIG. 3 shows a preferred embodiment of the dehumidi- fication elementand the structure in the vicinity of the dehumidification element, whichmay be employed in the present invention,

FIG. 4 is another preferred embodiment of the dehumidi- fication elementand the structure in the vicinity of the dehumidification element, whichmay be employed in the present invention,

FIG. 5 is a partially cut off perspective view of a preferred embodimentof the dehumidification apparatus according to the present invention,

FIG. 6 is a schematic view showing the structure of the drain panemployed in a preferred embodiment of the dehumidification apparatusaccording to the present inven- tion shown in FIG. 5,

FIG. 7 shows a circuit of the dehumidification apparatus according tothe present invention shown in FIG. 5

FIG. 8 is a psychrometric chart of the present invention and of theknown dehumidification apparatus shown in FIG. 1,

FIG. 9 shows a circuit of the dehumidification apparatus according to anembodiment of the present invention,

FIG. 10 shows a circuit of the dehumidification apparatus according toan embodiment of the present invention,

FIG. 11 shows a circuit of the dehumidification apparatus according toanother embodiment of the present invention,

FIG. 12 shows a circuit of the dehumidification apparatus according tostill another embodiment of the present invention,

FIG. 13 shows a circuit of the dehumidification apparatus according tostill another embodiment of the present invention,

FIG. 14 shows a circuit of the dehumidification apparatus according tostill another embodiment of the present inventor, and

FIG. 15 shows a circuit of the dehumidification apparatus according tostill another embodiment of the present inven- tion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the method for dehumidifying air according to the present invention,a dehumidification element (hereinafter also referred to as “DE” forshort) contained in a housing of a dehumidification apparatus which willbe described in detail later, is used. The DE has a moisture-absorbingmaterial at least at its surfaces. The moisture-absorbing material maybe any of the known moisture-absorbing materials including calciumchloride, lithium chloride, silica gel, molecular sieves and the like.The DE may be coated with or impregnated with such a moisture-absorbingmate- rial. Alternatively, the entire DE may be made of such amoisture-absorbing material. The DE preferably has a num- ber ofpassages penetrating therethrough. In this case, the surfaces of theinner walls of the passages has the above- mentioned moisture-absorbingmaterial. The passages may preferably have a diameter of 0.5-3 mm,although the diameter is not restricted to this range. The DE may pref-erably in the form of a plate or block, more preferably in the form of adisk. In this case, the passages may preferably be formed in thedirection of thickness thereof. Such a DE may easily be prepared byspirally winding a corrugated board and coating the moisture-absorbingmaterial on the inner side of the passages formed of the corrugatedstructure of the board.

In step (i) of the dehumidification method according to the presentinvention, the air to be dehumidified is introduced to the DE by a fanor the like and is made to contact the moisture-absorbing material. In apreferred embodiment, the air is made to pass through the passagesformed in the DE. In the case where the DE is in the form of a plate orblock and has a number of passages therethrough, the air is made to passthrough the passages and reach the opposite side of the DE. During thepassing through, the moisture in the air is absorbed by themoisture-absorbing material at the sur- faces of the passages of the DE,so that the air is dehumidi- fied. The air to be dehumidified may bemade to contact the entire DE or a part of the DE, and the latter ispreferred as will be described hereinbelow.

In step (ii), the dehumidified air is discharged to the outside of thehousing of the dehumidification apparatus.

In step (iii), the DE after dehumidifying the air is regen- erated byremoving the moisture absorbed by the moisture-absorbing material of theDE. In the method of the present invention, air entirely used forregeneration of the DE is employed (this air is hereinafter alsoreferred to as “DE-regenerating air” for short). The DE is regeneratedby being made to contact the heated DE-regenerating air. By the contactwith the heated DE-regenerating air, the moisture contained in themoisture-absorbing material of the DE is given to the heatedDE-regenerating air, so that the DE is regenerated. In the preferredembodiment wherein the DE is in the form of a plate or block having anumber of passages penetrating therethrough in the direction ofthickness thereof, the DE-regenerating air is also made to pass throughthe passages so as to reach the other side of the DE, in the same manneras in the air to be dehumidified mentioned above.

In step (iv), the thus regenerated DE is reused in the above-mentionedstep (i).

In step (v), the DE-regenerating air after regeneration of the DE instep (iii) is cooled to condense the moisture contained therein, and thewater generated by the conden- sation of the moisture is removed fromthe DE-regenerating air. The DE-regenerating air may preferably becooled by exchanging heat with the air to be dehumidified which is inthe way to the DE in a heat exchanger. Before exchanging heat with theair to be dehumidified, the DE-regenerating air after regeneration ofthe DE may preferably be subjected to heat exchange with theDE-regenerating air to be heated for regenerating the DE. By step (v),the DE-regenerating air is dehumidified.

In step (vi), the thus dehumidified DE-regenerating air is circulated tothe DE and used for regenerating the DE in step (iii) after being heatedwith a heater. Before being heated with a heater, the DE-regeneratingair may preferably be heated by exchanging heat with the DE-regeneratingair which is to be cooled in a heat exchanger as mentioned above. TheDE-regenerating air may preferably be heated to a temperature of 60° C.to 300° C., although the temperature of the heated DE-regenerating airis not restricted thereto.

Thus, the regenerated DE in step (iii) is reused in step (i) (thisreusing step is designated as step (iv)), and the DE-regenerated airdehumidified in step (v) is reused in step (iii). Therefore, the steps(i) to (vi) described above may be repeated continuously.

In the dehumidification method according to the present invention, it isan important feature that the DE-regenerating air is not substantiallymixed with the air to be dehumidified or with the dehumidified air to bedischarged to the outside of the housing. This is accomplished by thefact that the route of the DE-regenerating air is completely closedexcept for the vicinity of the DE, so that the DE-regenerating air doesnot contact the air to be dehumidified or the dehumidi- fied air at allexcept for in the vicinity of the DE. In the vicinity of the DE,although the DE-regenerating air may more or less contact the air to bedehumidified and with the dehumidified air, by appropriately designingthe DE and the structure in the vicinity of DE as described below, themixing of the DE-regenerating air and the air to be dehu- midified orthe dehumidified air may be substantially avoided. Therefore, in thedehumidification method accord- ing to the present invention, theDE-regenerating air is not substantially mixed with the air to bedehumidified or with the dehumidified air to be discharged to theoutside of the housing.

A preferred embodiment for continuously carrying out the steps (i) to(vi) will now be described referring to FIG. 3 showing the DE and thestructure in the vicinity thereof.

In this preferred embodiment, the DE 9 is in the form of a disk and anumber of passages 32 penetrate the disk in the direction of thethickness of the disk (in FIG. 3, in the direction of left to right). Asmentioned above, a moisture-absorbing material is coated on the innerwalls of the passages 32. In the center of the DE 9, a penetrating hole34 for receiving a rotating shaft (not shown) is formed. A surface 33 ofthe DE 9 at which the passages 32 are opened is herein called a firstsurface (in FIG. 3, the left side of the disk) and the surface 35 of thedisk opposite to the first surface 33 is herein called a second surface.A region of the first surface 33 of the DE 9 is covered with a firstchamber 12 and another region of the first surface 33 is covered with asecond chamber 19. The region of the second surface 35 of the DE 9opposite to the first chamber 12 is covered with a third chamber 13 andthe region of the second surface 35 of the DE 9 opposite to the secondchamber 19 is covered with a fourth chamber 20. The first chamber 12 andthe second chamber 19 are connected through a separation portion 36, andsimilarly, the third chamber 13 and the fourth chamber 20 are connectedthrough a separation portion 36. In a preferred embodiment as shown inFIG. 3, the first to fourth chambers are formed by providing hollowportions in a cover 10 which encloses the entire DE.

In operation, air to be dehumidified is introduced into the firstchamber 12 as shown by an arrow 38 through an inlet 39. The air to bedehumidified passes through the passages 32 to reach the third chamber13. During the air passes through the passages 32, the moisturecontained in the air is absorbed by the moisture-absorbing materialcoated on the surfaces of the passages 32, so that the air which reachedthe third chamber 13 has been dehumidified. The thus dehu- midified airis then discharged from the third chamber 13 as shown by an arrow 40through an outlet 41 to the outside of the housing la through adehumidified air-discharging pas- sage (not shown).

Simultaneously, the heated DE-regenerating air is intro- duced into thesecond chamber 19 as shown by an arrow 42 through an inlet 43 and passesthrough the passages 32 to reach the fourth chamber 20. Since theDE-regenerating air introduced into the third chamber 19 has beenheated, the DE-regenerating air passing through the passages 32 receivesmoisture from the moisture-absorbing material, so that this region ofthe DE 9 is regenerated. The DE-regenerating air after regeneration ofthe DE 9 is then discharged from the fourth chamber 20 as shown by anarrow 44 through an outlet 45. The DE-regenerating air discharged fromthe fourth chamber 20 is then cooled to condense the moisture, thenheated as mentioned above, and then introduced again into the secondchamber 19 as shown by the arrow 42. It should be, noted that theDE-regenerating air may be introduced into the fourth chamber 20 and maybe discharged from the third chamber 19 after regeneration of the DE 9.

In the embodiment shown in FIG. 3, the DE 9 in the form of a diskrotates in the plane perpendicular to the drawing sheet, about therotation shaft (not shown) received in the through hole 34. Therefore,the regions covered with the first chamber 12 and the third chamber 13,respectively, are moved to the position covered with the second chamber19 and the fourth chamber 20, respectively. By this rotation, the regionof the DE 9 which received moisture from the air to be dehumidified ismoved to the position at which the DE 9 is regenerated, andsimultaneously, the regenerated region of the DE 9 is moved to theposition at which the DE 9 receives moisture from the air to bedehumidified. Thus, the above-mentioned steps (i) to (vi) may berepeated continuously.

The rotation of the DE 9 may be carried out by utilizing the weight ofthe moisture given to the moisture-absorbing material. That is, theregion of the DE 9 which received the moisture from the air to bedehumidified is heavier than the regenerated region of the DE 9.Therefore, as shown in FIG. 3, the region which received the moisture isin a higher position than the regenerated region, and the DE 9 naturallyrotates because of the gravity. Thus, in this embodiment, the DE 9 maybe rotated without any driving motor or the like. Alternatively, the DE9 may be rotated by a driving motor. In this case, the DE 9 may berotated continuously, or intermittently.

In the dehumidification method according to the present invention, thecirculation route of the DE-regenerating air is completely closed exceptfor in the vicinity of the DE 9. Therefore, the DE-regenerating air isnot mixed at all with any air in the circulation route except for in thevicinity of the DE 9. In the vicinity of the DE 9, since the inner sideof the first chamber 12 and the inner side of the second chamber 19 areconnected through a gap between the separation portion 36 and the firstsurface 33 of the DE 9, and since the inner side of the third chamber 13and the inner side of the fourth chamber 20 are connected through a gapbetween the separation portion 36 and the second surface 35 of the DE 9,the DE-regenerating air may be more or less mixed with the air to bedehumidified and with the dehu- midified air. However, since thepressure in the first chamber 12 and the second chamber 19 is about thesame, and since the pressure in the third chamber 13 and the fourthchamber 20 is about the same, the mixing of the DE-generating air withthe air to be dehumidified or the dehumidified air does notsubstantially occur. Further, by making the distance “d” of the gapbetween the separation portion 36 and the first surface 33, and of thegap between the separation portion 36 and the second surface 35 to besmall, preferably 1 mm to 4 mm, the mixing of the DE-regenerating airwith the air to be dehumidified or with the dehumidified air issubstantially avoided, so that the dehumidification efficiency is notsub- stantially decreased. The fact that the mixing does notsubstantially occur even if the distance “d” is as large as 4 mm is animportant advantage of the present invention, because in the knownapparatus which does not employ the DE-regenerating air separately, thedehumidification effi- ciency is decreased by 10% if the distance “d” isincreased by 1 mm. Therefore, according to the present invention, thetolerance of the dimensions of the DE 9 and the cover 10 is large, whichis very advantageous in assembling the appa- ratus.

Alternatively, by providing a separation strip (not shown) made of aflexible rubber or a plastic film in the gap so as to separate the firstchamber 12 and the second chamber 19, and the third chamber 13 and thefourth chamber 20, respectively, the mixing of the DE-regenerating airwith the air to be dehumidified or with the dehumidified air iscompletely avoided. In this case, the DE 9 may preferably be rotated bya driving motor in order to overcome the friction between the separationstrip and the DE 9. It should be noted that in the embodiment shown inFIG. 3, the distance “e” of the gap between the upper portion of the DE9 and the cover 10, and the gap between the lower portion of the DE 9and the cover 10, may also be preferably as small as possible,preferably 1 mm to 4 mm in order to substantially prevent the air to bedehumidified from being directly transferring to the third chamber 13without passing through the passages 32, and in order to substantiallyprevent the heated DE-regenerating air from being directly transferringto the fourth chamber 20 without passing through the passages 32.

The mixing of the DE-regenerating air with the air to be dehumidified orwith the dehumidified air may also be almost completely avoided by apreferred embodiment shown in FIG. 4. In this embodiment, the entire DE9 is enclosed in a cover 10 and the first to fourth chambers are formedby providing hollow portions, and the first to fourth chambers arespaced apart from each other. That is, the first chamber 12 and thesecond chamber 19 are spaced apart with a distance “f”, and the thirdchamber 13 and the fourth chamber 20 are spaced apart with a distance“f”. The distance “f” is larger than in the embodiment shown in FIG. 3.With the embodiment shown in FIG. 4, since the distance “f” is large,the mixing of the DE-regenerating air with the air to be dehumidified orwith the dehumidified air is substantially avoided. In this embodiment,the distance “f” may preferably be not shorter than the thickness of theDE, more preferably 1 to 5 times the thickness of the DE. Further, asshown in FIG. 4, the inlet or the outlet provided in each of thechambers may have the size equal to the chamber.

The apparatus for carrying out the above-described dehu- midificationmethod will now be described.

The dehumidification apparatus according to the present inventioncomprises a housing; a DE which reversibly absorbs moisture in the air;a passage for circulating the DE-regenerating air, which is communicatedto the dehu- midification element; means for introducing the air to bedehumidified to the DE; and a dehumidified air-discharging passage fordischarging the air dehumidified by the DE to the outside of thehousing, which is communicated to the dehumidification element and tothe outside of the housing. The passage for circulating DE-regeneratingair is provided with means for cooling the DE-regenerating air afterregen- erating the dehumidification element so as to condense themoisture removed from the DE; means for removing water generated bycondensation of moisture from DE-regenerating air; a heater for heatingthe DE-regenerating air after removing the water generated bycondensation of moisture; and driving means for circulating theDE-regenerating air. The passage for circulating the DE-regenerating airis closed everywhere except for the vicinity of the DE, so that themixing of the DE-regenerating air with the air to be dehumidified orwith the dehumidified air is substantially avoided, as described above.

A preferred embodiment of the dehumidification appara- tus according tothe present invention will now be described referring to FIG. 5.

The dehumidification apparatus 1 has a housing 1a in the form of a box.On the bottom of the housing 1a, a container 2 for receiving the watergenerated by condensation of moisture in the DE-regenerating air afterregeneration of the DE 9 is placed.

On the container 2, a first fan 4 and a second fan 5 are mounted, whichare rotated by a fan motor 3. The air outside the housing 1a is inhaledinto the housing 1a by the first fan 4 and is sent to a DE which is inthe form of a dehumidi- fication rotor 9 in this embodiment, throughpassages 6a of a heat exchanger 6 placed on the container 2, a chamber7, and a duct 8. The passages 6a are the passages of the heat exchanger,which are the lower half of the passages running horizontally in theheat exchanger.

The dehumidification rotor 9 is in the form of a disk and rotatablymounted in a cover 10 enclosing the entire dehu- midification rotor 9,the cover being called a dehumidifica- tion rotor case 10 in thisembodiment. The dehumidification rotor case 10 has the first to fourthchambers 12, 13, 19 and 20 as described above referring to FIG. 3. Theduct 8 is connected to the first chamber 12 and the air inhaled from theoutside of the housing 1a is sent to the first chamber 12 and the air isthen made to pass through the passages 32 (see FIG. 3) in thedehumidification rotor 9. The air which reached the third chamber 13,which has been dehumidified, is discharged from the third chamber 13through a duct 14 which is the dehumidification air-discharging passagemen- tioned above. The dehumidified air is discharged from the housing1a through the duct 14.

On the other hand, the DE-regenerating air is sent by the second fan 5to the passages 6b of the heat exchanger 6 through a duct 15. Thepassages 6b are the passages of the heat exchanger 6, which are theupper half of the passages running horizontally in the heat exchanger 6.The DE-regenerating air after passing through the passages 6b is sent toa chamber 17 having a heater 16 and heated with the heater 16. Theheated DE-regenerating air is then sent to the second chamber 19 in thedehumidification rotor case 10 through a duct 18.

The second chamber 19 and the fourth chamber 20 are smaller than thefirst chamber 12 and the third chamber 13, and the DE-regenerating airsent to the second chamber 19 then passes through the passages 32 (seeFIG. 3) of the dehumidification rotor 9 to reach the fourth chamber 20.

The DE-regenerating air which reached the fourth cham- ber 20 is thensent to the passages 6c of the heat exchanger 6 through a chamber 23provided above the heat exchanger 6. The passages 6c are the passages ofthe heat exchanger 6, which run in the vertical direction of the heatexchanger 6. In the heat exchanger 6, the passages 6c running in thevertical direction and the passages 6a and 6b running in the horizontaldirection are arranged alternately. That is, the passages 6a and 6b arearranged in vertical layers which are arranged with an interval., andthe gaps between each of the vertical layers harboring the horizontalpassages 6a and 6b define the vertical passages 6c.

When the DE-regenerating air passes down through the passages 6c, theDE-regenerating air is cooled and the moisture therein is condensed.After passing through the passages 6c, the DE-regenerating air reaches achamber 25 containing a drain pan 24 arranged below the heat exchanger6. The DE-regenerating air is then sent to the second fan 5 through aduct 26, and circulates again as described above. The condensed moisturegenerated by the cooling of the DE-regenerating air after regenerationof the dehumidifica- tion rotor 9 is dropped on the drain pan 24.

As shown in FIG. 6, a water-draining hole 24a is formed in the bottomcenter of the drain pan 24 and a float valve 27 is mounted on thewater-draining hole 24a. The float valve 27 comprises a valve body 27awhich opens and closes the water-draining hole 24a, and a float 27bmounted on the valve body 27a. When the water is accumulated in thedrain pan 24, the float 27b, and accordingly, the valve body 27a arefloated so that the valve is opened, and the water accumulated in thedrain pan 24 is discharged into the container 2 through thewater-draining hole 24a.

In operation, an electric power source (not shown) is turned on to drivethe fan motor 3 and to heat the heater 16. By the fan motor 3, the firstfan 4 and the second fan 5 are rotated. The air inhaled into the housing1a through an inlet (not shown) by the first fan 4 reaches thedehumidification rotor 9 through passages 6a of the heat exchanger 6,and is dehumidified when it passes through the passages 32 of thedehumidification rotor 9. The dehumidified air is discharged from anoutlet (not shown) by the first fan 4. By this dehumidification, thedehumidification rotor 9 absorbs the moisture in the air and the regionof the rotor 9 between the first chamber 12 and the third chamber 13becomes heavier than the region of the rotor 9 between the secondchamber 19 and the fourth chamber 20, so that the rotor 9 naturallyrotates in the direction shown by an arrow in FIG. 5.

On the other hand, the DE-regenerating air driven by the second fan 5reaches the heater 16 through the passages 6b of the heat exchanger 6,and heated by the heater 16. The heated DE-regenerating air then passesthrough the passages 32 in the rotor 9. The rotor 9 is naturally rotatedby gravity because of the weight of the absorbed moisture as mentionedabove, so that the region of the rotor 9 between the first chamber 12and the third chamber 13 comes to the position between the secondchamber 19 and the fourth chamber 20. Since the heated DE-regeneratingair passes through the passages 32 which has already absorbed themoisture, the moisture is given to the heated DE-regenerating air sothat the region of the rotor 9 between the second chamber 19 and thefourth chamber 20 is regenerated, that is, this region of the rotor 9regains the ability to absorb moisture from the air to be dehumidified.The thus regenerated region is then moved to the position between thefirst chamber 12 and the third chamber 13 by the natural rotationmentioned above, and absorbs the moisture in the air to be dehumidifiedas mentioned above.

The DE-regenerating air after regeneration of the rotor 9, which has ahigh temperature and high humidity, then passes through the passages 6cof the heat exchanger 6 and cooled during the passage through thepassages 6c by exchanging heat with the air passing through the passages6a and 6b. By this cooling, dew drops are formed on the surfaces of thepassages 6c.

The DE-regenerating air after passage through the pas- sages 6c has atemperature higher than the air passing through the passages 6a, and hasa relative humidity of 100%, so that its absolute humidity is higherthan that of the air outside the housing 1a. The DE-regenerating airthus having a high humidity is inhaled by the second fan 5 and is sentto the duct 15 to circulate the above-described route without beingdischarged from the housing 1a.

The dew drops formed on the surfaces of the passages 6c of the heatexchanger 6 are collected in the drain pan 24. The water-draining hole24a formed in the bottom of the drain pan 24 is stopped by the floatvalve 27 so as to prevent air flow, but when the water (dew drops)accumulates in the drain pan 24, the float 27b is floated, so that thevalve is opened. As a result, the water is drained into the container 2through the water-draining hole 24a.

The amount of the water accumulated in the container 2 is thedehumidification amount of this dehumidification apparatus. When thewater accumulates to an appropriate level, the container 2 is taken outof the housing 1a, and the water is discarded.

The circuit of this embodiment is shown in FIG. 7.

It may be well understood from FIG. 7 that the circulation route of theDE-regenerating air is separate from the path of the air to bedehumidified and the dehumidified air, so that the DE-regenerating airis not substantially mixed with the air to be dehumidified and thedehumidified air.

A psychrometric chart of the present invention and the above-describedprior art is shown in FIG. 8.

With the known apparatus described above, the air at the position{circle around (1)} is inhaled into the apparatus and heated by the heatexchanger E and the heater G to have a high tempera- ture (position{circle around (2)}). The air is then passed through thedehumidification rotor C to become humid (position {circle around (3)}),and then cooled by the heat exchanger E. Assuming the heat exchangeefficiency is 100% for the purpose of comparison with the presentinvention, the air is cooled to the tempera- ture t (position {circlearound (4)}), and the moisture of the dehumidification amount A iscondensed to form dew.

On the other hand, with the apparatus according to the presentinvention, the temperature of the DE-regenerating air at the exit of thepassages 6c of the heat exchanger 6 is “t” if the heat exchangeefficiency is 100%, and the relative humidity is 100% (position {circlearound (4)}).

By heating this DE-regenerating air with the same energy as used in theknown apparatus just mentioned above (heated amount B), the air comes tohave a high temperature (position {circle around (5)}). By passingthrough the dehumidification rotor 9, the air becomes humid (position{circle around (6)}), and by cooling the humid air by the heat exchangerto the temperature t (position {circle around (4)}), the moisture of thedehumidification amount B is condensed to form dew.

As can be seen from FIG. 8, by employing DE-regenerating air whichcirculates without being dis- charged from the apparatus, thedehumidification amount is larger than that of the known apparatus whenthe same energy is used for heating.

It will be apparent for those skilled in the art that thedehumidification apparatus according to the present inven- tion is notrestricted to the embodiment described above. For example, although theDE-regenerating air is passed through the passages 6b before beingheated by the heater 16 in the above-described embodiment, this passagethrough the heat exchanger is not necessary. Further, to cool theDE-regenerating air after regeneration of the DE, the air outside thehousing 1a may be introduced into the heat exchanger 6.

As shown in FIGS. 5 and 7, in the above-described embodiment, heat isexchanged between the DE-regenerating air after cooled and before heatedand the DE-regenerating air after regeneration of the DE-regeneratingair, thereby cooling the DE-regenerating air after regeneration of theDE and preheating the DE-regenerating air before heated by the heater.However, as shown in FIG. 9, this heat exchange may be omitted, and theDE-regenerating air after regeneration of the DE may be cooled only withthe air to be dehumidified.

Further, as shown in FIGS. 10 and 11, the air to be dehumidified whichis heated by the heat exchange with the DE-regenerating air afterregeneration of the DE and after giving heat to the DE-regenerating airbefore being heated with the heater may be sent to the DE and may befurther heated by the reaction heat generated when the DE absorbsmoisture. The thus further heated air may then be subjected to heatexchange with the cooled DE-regenerating regener- ating air therebyrecovering the heat generated by he cooling and moisture absorption.

Further, as shown in FIGS. 12 to 15, the route for sending the air to bedehumidified to the DE and the route for sending cooling air to the heatexchanger for cooling the DE-regenerating air after regeneration of theDE may be separated. By this, the decrease in the dehumidificationefficiency due to the decrease in the relative humidity caused byheating the air to be dehumidified by the heat exchange withDE-regenerating air after regeneration of the DE and after giving heatto the DE-regenerating air before being heated with the heater can beavoided. Further, since the DE and the heat exchanger for cooling theDE-regenerating air after regeneration of the DE are arranged inparallel, not in series as in the embodiment shown in FIGS. 7, 9 to 11,the pressure drop is decreased so that the pressure in the vicinity ofthe DE is close to the pressure outside the housing, and the pressure ofthe DE-regenerating air is close to the pressure outside the housing. Asa result, mixing of the DE-regenerating air and the air outside thehousing hardly occurs, so that the decrease in the dehumidificationeffi- ciency can be avoided.

Further, fan motors may be arranged in appropriate posi- tions in theroute and the heat generated by the motor may be recovered. Stillfurther, as shown in FIGS. 11 and 15, the exit of the dehumidified airmay be divided and only the hot air may be subjected to heat exchangewith the DE-regenerating air. That is, since the DE immediately afterregeneration rapidly absorbs moisture, the temperature of the airdehumidified by the DE immediately after regenera- tion is higher thanthe temperature of the air dehumidified by the DE which has alreadyabsorbed some amount of mois- ture. Thus, the exit of the dehumidifiedair may be divided such that the air dehumidified by the DE immediatelyafter regeneration is divided with the air dehumidified by the DE whichhas already absorbed moisture, and only the hotter air dehumidified withthe DE immediately after regeneration may be subjected to heat exchangewith the DE-regenerating air.

According to the apparatus described above, since the DE-regeneratingair entirely used for regeneration of the dehumidification element isseparately employed and is circulated without being discarded andwithout being sub- stantially mixed with the air to be dehumidified orwith the dehumidified air, the dehumidification efficiency is signifi-candy higher than those with the conventional dehumidifi- cationapparatuses wherein the humid air is discharged to the outside of theapparatus.

Further, with the apparatus according to the present invention, sincethe air to be dehumidified and the DE-regenerating air are driven byseparate fans, the pres- sures in the first chamber 12 and the secondchamber 19 are the same, and the pressures in the third chamber 13 andthe fourth chamber 20 are the same. Therefore, air does not flow betweenthe first chamber 12 and the second chambers 19, and between the thirdchamber 13 and the fourth chamber 20. As a result, even if the gap “d”is relatively large, the DE-regenerating air is not substantially mixedwith the air to be dehumidified or with the dehumidified air. Therefore,the dehumidification efficiency is high and the tolerance of thedimensions of the dehumidification rotor 9 and the rotor case 10 islarge, which is very advantageous in assembling the apparatus. Stillfurther, since the gap “d” may be relatively large, it can be avoidedthat the rotor 9 does not rotate because of the dust accumulated betweenthe rotor 9 and the rotor case 10.

1. A method for dehumidifying air comprising the steps of: (i)contacting a dehumidification element which revers- ibly absorbsmoisture in the air and which is contained in a housing of adehumidification apparatus, with the air to be dehumidified; (ii)discharging air to the outside of said housing, which air wasdehumidified by the contact with said dehu- midification element; (iii)regenerating said dehumidification element by con- tacting saiddehumidification element after absorbing the moisture in said air withheated air for regeneration of the dehumidification element so as toremove the moisture from said dehumidification element; (iv) reusing thedehumidification element in the step (i), which was regenerated by thestep (iii); (v) cooling the air for regeneration of the dehumidifica-tion element after removing moisture from the dehu- midification elementin the step (iii) so as to condense the moisture, removing the generatedwater from the air for regeneration of the dehumidification element andcollecting the water generated by the condensation of the moisturewithout allowing air leakage into or from the dehumidificationapparatus; and (vi) circulating the air for regeneration of thedehumidi- fication element from the step (v) from which the watergenerated by condensation of moisture was removed, to the step (iii);said air for regeneration of the dehumidification element is notsubstantially mixed with the air to be dehumidified or with thedehumidified air.
 2. The method according to claim 1, wherein said airfor regeneration of the dehumidification element is not mixed with theair to be dehumidified or with the dehumidified air anywhere except forthe vicinity of said dehumidification element.
 3. The method accordingto claim 1, wherein said dehu- midification element is made of amaterial which has a moisture-absorbing material at least at itssurfaces, and which has a number of passages, and said air to be dehu-midified and said air for regeneration of the dehumidifica- tion elementpass through said passages.
 4. The method according to claim 3, whereinsaid dehu- midification element is in the form of plate or block whichhas a number of passages in the direction of thickness thereof.
 5. Themethod according to claim 4, wherein said dehu- midification element isrotatable, a region of a first surface thereof at which said passagesare opened is covered with a first chamber and another region of saidfirst surface is covered with a second chamber, and a region of a secondsurface of said dehumidification element opposite to said first surfaceis covered with a third chamber and another region of said secondsurface is covered with a fourth chamber; said air to be dehumidifiedbeing introduced into said first chamber, passing through said passagesto reach said third chamber, and being discharged from said thirdchamber to the outside of said housing through a dehumidifiedair-discharging passage; p1 said air for regeneration of thedehumidification element being introduced into said second chamber,passing through said passages to reach said fourth chamber, and beingcirculated to the step (v) from said fourth chamber; said regions of thedehumidification element covered with said first and third chambers,respectively, are moved by rotation of said dehumidification element tothe position covered with said second and fourth chambers, respectively.6. The method according to claim 4, wherein said dehu- midificationelement is rotatable, a region of a first surface thereof at which saidpassages are opened is covered with a first chamber and another regionof said first surface is covered with a second chamber, and a region ofa second surface of said dehumidification element opposite to said firstsurface is covered with a third chamber and another region of saidsecond surface is covered with a fourth chamber; said air to bedehumidified being introduced into said first chamber, passing throughsaid passages to reach said third chamber, and being discharged fromsaid third chamber to the outside of said housing through a dehumidifiedair-discharging passage; said air for regeneration of thedehumidification element being introduced into said fourth chamber,passing through said passages to reach said second chamber, and beingcirculated to the step (v) from said second chamber; said regions of thedehumidification element covered with said first and third chambers,respectively, are moved by rotation of said dehumidification element tothe position covered with said second and fourth chambers, respectively.7. The method according to claim 5, wherein said first to fourthchambers are formed by providing hollow portions in a cover whichencloses the entire dehumidification element, and said first to fourthchambers are spaced apart from each other.
 8. The method according toclaim 6, wherein said first to fourth chambers are formed by providinghollow portions in a cover which encloses the entire dehumidificationelement, and said first to fourth chambers are spaced apart from eachother.
 9. The method according to claim 1, wherein said air forregeneration of the dehumidification element is cooled in the step (v)by giving heat of the air for regeneration of the dehumidificationelement to the air to be dehumidified in a heat exchanger.
 10. Adehumidification apparatus comprising: a housing; a dehumidificationelement which reversibly absorbs moisture in air; a passage forcirculating air for regeneration of the dehumidification element, whichis communicated to said dehumidification element; a device forintroducing the air to be dehumidified to said dehumidification element;and a dehumidified air-discharging passage for discharging the airdehumidified by said dehumidification element to the outside of saidhousing, which is communicated to said dehumidification element and tothe outside of said housing; said passage for circulating air forregeneration of the dehumidification element is provided with a devicefor cooling the air for regeneration of the dehumidification elementafter regenerating the dehumidification ele- ment so as to condense themoisture removed from the dehumidification element; a device forremoving water generated by condensation of moisture from the air forregeneration of the dehumidification element; a device for collectingthe water generated by the condensation of the moisture without allowingair leakage into or from the dehumidification apparatus; a heater forheat- ing the air for regeneration of the dehumidification element; aheater for heating the air for regeneration of the dehumidificationelement after removing the water generated by condensation of moisture;and a driving device for circulating the air for regeneration of thedehumidification element; said passage for circulating air forregeneration for regen- eration of the dehumidification element isclosed any- where except for the vicinity of said dehumidificationelement.
 11. The apparatus according to claim 10, wherein saiddehumidification element is made of a material which has amoisture-absorbing material at least at its surfaces and which has anumber of passages, and said air to be dehu- midified and said air forregeneration of the dehumidifica- tion element pass through saidpassages.
 12. The apparatus according to claim 10, wherein saiddehumidification element is in the form of plate or block which has anumber of passages in the direction of thickness thereof.
 13. Theapparatus according to claim 12, wherein said dehumidification elementis rotatable, a region of a first surface thereof at which said passagesare opened is covered with a first chamber and another region of saidfirst surface is covered with a second chamber, and a region of a secondsurface of said dehumidification element opposite to said first surfaceis covered with a third chamber and another region of said secondsurface is covered with a fourth chamber; said air to be dehumidifiedbeing introduced into said first chamber, passing through said passagesto reach said third chamber, and being discharged from said thirdchamber to the outside of said housing through a dehumidifiedair-discharging passage; said air for regeneration of thedehumidification element being introduced into said second chamber andpassing through said passages to reach said fourth chamber, and saidfourth chamber being connected to said passage for circulating the airfor regeneration of the dehumidi- fication element; said regions of thedehumidification element covered with said first and third chambers,respectively, are moved by rotation of said dehumidification element tothe position covered with said second and fourth chambers, respectively.14. The apparatus according to claim 12, wherein said dehumidificationelement is rotatable, a region of a first surface thereof at which saidpassages are opened is covered with a first chamber and another regionof said first surface is covered with a second chamber, and a region ofa second surface of said dehumidification element opposite to said firstsurface is covered with a third chamber and another region of saidsecond surface is covered with a fourth chamber; said air to bedehumidified being introduced into said first chamber, passing throughsaid passages to reach said third chamber, and being discharged fromsaid third chamber to the outside of said housing through a dehumidifiedair-discharging passage; said air for regeneration of thedehumidification element being introduced into said fourth chamber andpassing through said passages to reach said second chamber, and saidsecond chamber being connected to said passage for circulating the airfor regeneration of the dehumidification element; said regions of thedehumidification element covered with said first and third chambers,respectively, are moved by rotation of said dehumidification element tothe position covered with said second and fourth chambers, respectively.15. The apparatus according to claim 13, wherein said first to fourthchambers are formed by providing hollow portions in a cover whichencloses the entire dehumidification element, and said first to fourthchambers are spaced apart from each other.
 16. The apparatus accordingto claim 14, wherein said first to fourth chambers are formed byproviding hollow portions in a cover which encloses the entiredehumidification element, and said first to fourth chambers are spacedapart from each other.
 17. The apparatus according to claim 10, whereinsaid device for cooling the air for regeneration of the dehumidi-fication element after regenerating the dehumidification ele- ment so asto condense the moisture removed from the dehumidification element is aheat exchanger, and heat is exchanged between said air for regenerationof the dehu- midification element after regeneration of the dehumidifi-cation element and the air to be dehumidified.
 18. The apparatusaccording to claim 10, wherein said dehumidification element is in theform of a rotatable disk.
 19. The apparatus according to claim 10,wherein said device for introducing the air to be dehumidified to thedehumidification element is a first fan, and the apparatus furthercomprising a second fan for circulating said air for regeneration of thedehumidification element.